GPS satellites transmit GPS signals at two frequencies, referred to as the L1 and L2 frequencies. The L1 frequency is 1575.42 MHz. The L2 frequency is 1227.60 MHz. The GPS signals are right-hand circularly polarized.
GPS antennae are used to receive GPS signals. Because the received GPS signals are typically low-power, GPS antennae can be jammed by bombarding the antennae with interfering signals. A GPS antenna having N receiving elements can resist jamming signals propagating from N−1 locations.